Baba Basra 7:1-2

Baba Basra 7:1

Let’s say that one person tells another that he is selling him enough land to plant a kor of grain (about 75,000 square cubits). If there are cracks in the ground ten handbreadths deep (about 30”) or rocks ten handbreadths tall, they don’t count towards the land being sold (because this land is not usable). If they are smaller than that, then they do count. If one merely says that he is selling a kor’s worth of land, then even if the cracks are deeper than ten handbreadths, or the rocks taller than this, they count towards the land being sold.

Baba Basra 7:2

If he says that he is selling a kor’s worth of land as measured with a rope, then the price must be adjusted to reflect any difference between a kor and the actual size of the land. If he said that he is selling a kor “more or less,” then even a variation of a quarter seah up or down is acceptable. (This is 1/24 of the overall area being sold.) If the difference is greater than that, they must adjust the price. In the case of an overage, the buyer must pay for the excess land, though if the seller prefers, he can just take the extra land back. The reason they said the buyer must pay the difference is to give the seller the upper hand in this situation (because if the buyer had the option, he might choose to give the seller a piece of land too small to be of any use). If the surplus land in a field is enough to plant nine kav, or if the surplus land in a garden is enough to plant half a kav - or, according to Rabbi Akiva, a quarter kav - then the buyer must return the surplus land - not just the part that exceeds 1/24 but the entire surplus.